Are you using an old version of AGS? If so, there's no global variables pane in the editor. You'd have to use Global ints or import/export variables you created in the global script. Otherwise just do what Khris said, he gave you an example.
So what's the problem, doesn't it work? As Khris said: Give us more info if you want to get help.
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my intention was to enable a hotspot only if there are all three items activated in my inventory, probably there is an other possibility to achieve the desired result
So what's the problem, doesn't it work? As Khris said: Give us more info if you want to get help.